The Tack Rules
Remove every active cause before judging whether a root-cause intervention worked.
- Difficulty
- Easy
- Time to result
- ~days to results
- Steps
- 5
- Confidence
- 99%
The Tack Rules use a physical analogy to improve causal reasoning. If someone is standing on one tack, piling on cushioning does not solve the core problem; remove the tack. If the person is standing on two tacks, removing one does not make the experience half as painful because the remaining tack can still produce the full symptom. Applied more broadly, the model says that several independent causes may each be sufficient to sustain an outcome. Therefore, a partial intervention can look ineffective even when it correctly addressed one cause. The method is to identify all plausible sustaining inputs, remove those that can be safely tested, observe the result, and only then judge the causal hypothesis.
Origin
Extracted from Habits & Hustle. Dr. Mark Hyman attributed the Tack Rules to his mentor Sydney Baker and applied them to simultaneous food sensitivities.
Core principles
- 01A continuing cause can mask improvement elsewhere.
- 02Removing one of several causes does not guarantee partial relief.
- 03Stop adding compensations before removing the irritant.
- 04Judge an intervention only after the relevant causes are absent.
How to run it
- 1
Define the painful outcome
State precisely what symptom, bottleneck, or failure remains unresolved.
Pro tip Use an observable outcome rather than a vague feeling.
Watch out Do not use the analogy to dismiss the need for diagnosis.
- 2
Find the tacks
List factors that could each independently maintain the unwanted outcome.
Pro tip Ask which cause could preserve the full problem even if others disappeared.
Watch out Do not label speculation as established causation.
- 3
Remove causes before adding fixes
Where safe, eliminate the maintaining inputs instead of layering compensations over them.
Pro tip Begin with reversible, high-likelihood causes.
Watch out Some medications, foods, or exposures cannot be stopped abruptly.
- 4
Test the complete causal set
Remove all safely testable sustaining causes for a defined period rather than testing an incomplete subset.
Pro tip Keep unrelated variables stable.
Watch out Simultaneous removal identifies a causal set, not necessarily the individual cause.
- 5
Interpret the result
Improvement supports the causal set; nonresponse means another tack may remain or the model may be wrong.
Pro tip Document both expected and unexpected changes.
Watch out Absence of immediate relief does not always prove absence of causation.
In the wild
A person reacts independently to gluten and dairy. Removing gluten while continuing dairy produces little improvement, leading them to believe gluten was irrelevant. Removing both for a controlled period finally tests whether the pair sustains the symptoms.
→ The complete elimination can reveal a combined causal set that a partial test missed.
Common mistakes
Expecting proportional relief
When either cause can sustain the outcome, removing half the causes may produce no noticeable percentage improvement.
Adding cushions indefinitely
Supplements, medications, or workarounds may mask effects while the underlying irritant remains active.
Confusing group removal with isolation
Removing several variables together can show that the group matters, but it does not identify which member caused which effect.
Is it for you?
Best for
It is best for troubleshooting situations where multiple simultaneous inputs may each sustain the same unwanted outcome.
Not ideal for
It is not ideal when removing several variables together would be unsafe or when identifying the individual causal contribution is essential.
From the transcript
“There's a rule in functional medicine called the tack rules by my mentor Sydney Baker.”
“if you're standing on a tack, it takes a lot of astro to make it feel better. So take out the tack, get rid of…”
“And you're standing on two tacks, taking one of them out doesn't make you 50% better.”
From the episode
Episode 401: Dr. Mark Hyman: Why Only 6.8% of Americans are Healthy + His Recommended Anti-Aging Solutions
Dr. Mark Hyman